Gamma-ray spectroscopy may be performed using a scintillator (e.g. NaI) or a diode where the gamma-ray energy response depends on the resolution of the detector. Scintillators are certain to within about 10% of the energy, and diodes to within about 0.1%. High-purity germanium (HPGe) radiation detectors are one type of diode detector known for their performance and reliability characteristics and have become a standard by which other radiation detectors are compared. HPGe detector systems have long been the standard for critical applications including uranium enrichment and plutonium isotopic analysis, among others. Combining this high performance with the additional property of high efficiency, HPGe detectors provide very high resolution radio-nuclide spectra within a minimum acquisition time. Therefore, HPGe detector systems are recognized as a basic tool for isotopic analysis.
The better diode performance, however, comes at the price of complexity. HPGe detector systems have typically required extensive support equipment, such as signal processing electronics for data acquisition (shaping amplifier, test pulser), a high voltage power supply for detector bias, a multi-channel analyzer (MCA), a computer including requisite software necessary for spectral analysis, and a continuous supply of liquid nitrogen (LN) to maintain the detector at its proper operating temperature. The requirement of liquid cryogens for cooling the diode are especially taxing on such detector systems by increasing weight and power requirements. And low noise signal processing electronics consume large amounts of power, requiring a high capacity power source. As a result, HPGe detectors have typically been utilized only in the laboratory, and not for field operation. Moreover, building a radiation detector utilizing the desirable diode detector has usually resulted in systems that are not highly portable by humans, such as handheld detectors.
In summary, what is needed is an improved radiation detection system, such as an HPGe gamma-ray detector, which addresses power requirements, weight, and other limitations traditionally present with diode detectors, to enable field portability, such as by handheld operation or toting on a user's person.